Chelation behavior of various flavonols and transfer of flavonol-chelated zinc(II) to alanylaspartic dipeptide: A PCM/DFT investigation

Yasarawan, Nuttawisit; Thipyapong, Khajadpai; Ruangpornvisuti, Vithaya

doi:10.1016/j.molstruc.2015.11.059

Cited by 7 publications

(6 citation statements)

References 71 publications

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“…Molecular structures of Zn(II)-Kaem complexes and Kaem for comparison were optimized using DFT method and are shown in Figure S5. Hexa-coordinate structures of all Zn(II)-Kaem complexes are more stable than tetracoordinated as indicated by imaginary frequencies found in frequency calculation for tetracoordination . In the optimized structures of both 1:1 and 1:2 Zn(II)-Kaem complexes, Zn(II) ion coordinate to oxygen atoms of Kaem.…”

Section: Resultsmentioning

confidence: 92%

“…Hexa-coordinate structures of all Zn(II)-Kaem complexes are more stable than tetracoordinated as indicated by imaginary frequencies found in frequency calculation for tetracoordination. 52 In the optimized structures of both 1:1 and 1:2 Zn(II)-Kaem complexes, Zn(II) ion coordinate to oxygen atoms of Kaem. The other coordination sites in octahedron are occupied by solvent ethanol, not shown in Figure S5 20 However, both suggestions lack experimental evidence.…”

Section: Dpphmentioning

confidence: 99%

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Kaempferol Binding to Zinc(II), Efficient Radical Scavenging through Increased Phenol Acidity

Qian

Yang

et al. 2018

J. Phys. Chem. B

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Zinc(II) enhances radical scavenging of the flavonoid kaempferol (Kaem) most significantly for the 1:1 Zn(II)-Kaem complex in equilibrium with the 1:2 Zn(II)-Kaem complex both with high affinity at 3-hydroxyl and 4carboxyl coordination. In methanol/chloroform (7/3, v/v), 1:1 Zn(II)-Kaem complex reduces β-carotene radical cation, β-Car •+ , with a second-order rate constant, 1.88 × 10 8 L• mol −1 •s −1 , while both Kaem and 1:2 Zn(II)-Kaem complex are nonreactive, as determined by laser flash photolysis. In ethanol, 1:1 Zn(II)-Kaem complex reduces the 2,2-diphenyl-1-picrylhydrazyl radical, DPPH • , with a second-order rate constant, 2.48 × 10 4 L•mol −1 •s −1 , 16 times and 2 times as efficient as Kaem and 1:2 Zn(II)-Kaem complex, respectively, as determined by stopped-flow spectroscopy. Density functional theory calculation results indicate significantly increased acidity of Kaem as ligand in 1:1 Zn(II)-Kaem complex other than in 1:2 Zn(II)-Kaem complex. Kaem in 1:1 Zn(II)-Kaem complex loses two protons (one from 3-hydroxyl and one from phenolic hydroxyl) forming 1:1 Zn(II)-(Kaem−2H) during binding with Zn(II), while Kaem in 1:2 Zn(II)-Kaem complex loses one proton in each ligand forming Zn(II)-(Kaem−H) 2 , as confirmed by UV−vis absorption spectroscopy. Zn(II)-(Kaem−2H) is a far stronger reductant than Kaem and Zn(II)-(Kaem−H) 2 as determined by cyclic voltammetry. Significant rate increases for the 1:1 complex in both β-Car •+ scavenging by electron transfer and DPPH • scavenging by hydrogen atom transfer were ascribed to decreases of ionization potential and of bond dissociation energy of 4′-OH for deprotonated Zn(II)-(Kaem−2H), respectively. Increased phenol acidity of plant polyphenols by 1:1 coordination with Zn(II) may explain the unique function of Zn(II) as a biological antioxidant and may help to design nontoxic metal-based drugs derived from natural bioactive molecules.

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Section: Resultsmentioning

confidence: 92%

Section: Dpphmentioning

confidence: 99%

Kaempferol Binding to Zinc(II), Efficient Radical Scavenging through Increased Phenol Acidity

Qian

Yang

et al. 2018

J. Phys. Chem. B

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“…Second, at the same time of showing free rotation (as observed for M3), it was identified that M2 presents an acid hydrogen (depicted in a light blue area) resulting from the removal of electron density by the inductive effect of the amide nitrogen. This acid hydrogen enables ALGM2 to form supramolecular hydrogen bonds with neighbor polymer chains [43], reinforcing to some extent the crosslinking joints expected to occur by the C=C reactive bond. And third, it was also found that ALGM1 presents an intramolecular hydrogen bond in its methacrylate unit (OH-O), displaying an in-between distance of 1.61 Å and an angle of 161.29 • , which correspond to a rather strong hydrogen bonding [44].…”

Section: Density Functional Calculationsmentioning

confidence: 81%

Photocrosslinked Alginate-Methacrylate Hydrogels with Modulable Mechanical Properties: Effect of the Molecular Conformation and Electron Density of the Methacrylate Reactive Group

et al. 2020

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Hydrogels for load-bearing biomedical applications, such as soft tissue replacement, are required to be tough and biocompatible. In this sense, alginate-methacrylate hydrogels (H-ALGMx) are well known to present modulable levels of elasticity depending on the methacrylation degree; however, little is known about the role of additional structural parameters. In this work, we present an experimental-computational approach aimed to evaluate the effect of the molecular conformation and electron density of distinct methacrylate groups on the mechanical properties of photocrosslinked H-ALGMx hydrogels. Three alginate-methacrylate precursor macromers (ALGMx) were synthesized: alginate-glycidyl methacrylate (ALGM1), alginate-2-aminoethyl methacrylate (ALGM2), and alginate-methacrylic anhydride (ALGM3). The macromers were studied by Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), and density functional theory method (DFT) calculations to assess their molecular/electronic configurations. In parallel, they were also employed to produce H-ALGMx hydrogels, which were characterized by compressive tests. The obtained results demonstrated that tougher hydrogels were produced from ALGMx macromers presenting the C=C reactive bond with an outward orientation relative to the polymer chain and showing free rotation, which favored in conjunction the covalent crosslinking. In addition, although playing a secondary role, it was also found that the presence of acid hydrogen atoms in the methacrylate unit enables the formation of supramolecular hydrogen bonds, thereby reinforcing the mechanical properties of the H-ALGMx hydrogels. By contrast, impaired mechanical properties resulted from macromer conditions in which the C=C bond adopted an inward orientation to the polymer chain accompanied by a torsional impediment.

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“…It is especially the case of the complex formed between morin and the Zn II cation. [5][6][7][8][9][10] Figure 1: Structure of two conformers of morin along with the conventional numbering of atoms (blue) and labelling of rings (red). The number describing the atoms of a substituant is the same as the one of the bearing skeleton atom.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, no study associates both computations and experiments that is, as stated before, a good way to compensate for the limitations of each aspect. Notably, the environment is also not fully considered in these publications, especially the computational ones: the protonation state of morin is either assumed without justification 10 or chosen on the basis of the lability of proton in free morin 6 , and possible solvent molecules in the coordination sphere of the cation are often neglected. Therefore, we chose to re-investigate this system using the methodology we developed in our group.…”

Section: Introductionmentioning

confidence: 99%

The crucial role of the inter-ring hydrogen bond to explain the properties of morin

et al. 2018

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Chelation behavior of various flavonols and transfer of flavonol-chelated zinc(II) to alanylaspartic dipeptide: A PCM/DFT investigation

Cited by 7 publications

References 71 publications

Kaempferol Binding to Zinc(II), Efficient Radical Scavenging through Increased Phenol Acidity

Kaempferol Binding to Zinc(II), Efficient Radical Scavenging through Increased Phenol Acidity

Photocrosslinked Alginate-Methacrylate Hydrogels with Modulable Mechanical Properties: Effect of the Molecular Conformation and Electron Density of the Methacrylate Reactive Group

The crucial role of the inter-ring hydrogen bond to explain the properties of morin

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